Method of lifting a heavy component for sensitive engagement with another

ABSTRACT

The method of lifting a heavy first component for sensitive engagement with a second component wherein a spring-loaded device is engaged between a mechanical lifting means and the first component to neutralize the weight thereof when lifted, the reduced weight of the lifted component is moved manually into engagement with the second component and thereafter, any interference during completion of the engagement is manually sensed and corrected by manual adjustment of the vertical position of the first component relative to the mechanical lifting means.

United States Patent 1191 1111 3,792,787

Maloney Feb. 19, 1974 [5 METHOD OF LIFTING A HEAVY 3,621,756 11/1971 Ulbing 91 390 COMPONENT FOR SENSITIVE ENGAGEMENT WITH ANOTHER Primary ExaminerGerald M. Forlenza Inventor! William COhOeS, Assistant ExaminerGeorge F. Abraham [73] Assigneez The United States of America as Attorney, Agent, or FirmEdward J. Kelly; Herbert represented by the Secretary of the Ber]; Albert Arnold Army, Washington, DC.

[22] Filed: June 19, 1973 21 Appl. No.: 371,428 [57] ABSTRACT Related Application Data The method of lifting a heavy first component for sen- [63] Continuation-impart of Ser. No. 110,498, Jan. 28, sitive engagement with a second component wherein a 1971, abandoned. spring-loaded device is engaged between a mechanical lifting means and the first component to neutralize the Cl 214/152, 214/2, /658, weight thereof when lifted, the reduced weight of the 9 /8 R lifted component is moved manually into engagement [51] Int. Cl. B66c 1/34 with the second component and thereafter, any inter- Field Of Search 294/82 ference during completion of the engagement is man- 9 /340, 327 ually sensed and corrected by manual adjustment of the vertical position of the first component relative to [56] References Cited the mechanical lifting means.

UNITED STATES PATENTS 3,552,720 1/1971 McKendrick 254/135 R 1 Claim, 5 Drawing Figures l I E :1 72 l 1 1 H l 1 l 52 1 52 34 68* 1 i 58 2O 36 l l V 46 :46 E

PATENIED FEB I 9 I974 SHEET 2 0f 2 T i I I T METHOD OF LIFTING A HEAVY COMPONENT FOR SENSITIVE ENGAGEMENT WITH ANOTHER This application is a continuation-in-part of my copending patent application of the same title, Ser. No. ll0,498, filed Jan. 28, 1971, and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to methods for lifting heavy loads by mechanical means and pertains more particularly to an improved method for lifting a heavy component into position for engagement with a stationary component and thereafter maintaining a noninterfering alignment therebetween by manual adjustment of the lifted component relative to the mechanical lifting means.

In manufacturing operations it is oftentimes necessary to life a heavy component such as an inspection gauge, into position for engagement, as by horizontal insertion, with another component. This lifting has to be done by mechanical hoisting devices when the load is too heavy for easy manual manipulation, and because the lifting is done mechanically it is not possible for the operator to sensitively feel whether the two components are in perfect alignment as they are moved together to complete the required engagement therebetween. Consequently, misalignment frequently occurs and only a slighl deviation from alignment during engagement can cause galling or scoring to damage, sometimes beyond repair, one of the components with very costly results.

SUMMARY OF THE INVENTION It is therefore a principal object of this invention to provide a method of lifting a heavy component for sensitive engagement with another component whereby the weight of the lifted component is neautralized so that it may be easily manipulated manually during final engagement, and thereby any interference with the final engagement may be sensitively felt by the operator and corrected before any damage is done to either one of the components.

It is another object of this invention to provide such a method of lifting a heavy component for sensitive engagement with another component whereby the amount of manual force required to manipulate the lifted component is easily varied.

It is a further object of this invention to provide a method for lifting a heavy component for sensitive engagement with another which reduces to a minimum any bounding and buffeting of the lifted component during the manual manipulation thereof.

These objects are successfully achieved through the use of a weight neutralizing device operationally disposed between the hoist and the component to be lifted. The device includes a plurality of selected springs which are compressed by the weight of the lifted component to a position of zero equilibrium, whereby the component is easily manipulated manually by the operator who can sensitively feel any interference during the engagement. The surging action of the springs, as equilibrium is recovered after being unbalanced, is reduced by buffer devices so that bouncing and buffeting of the lifted component are eliminated as it is manually manipulated.

Further objects and advantages of the invention will be apparent from the following specification and the accompanying drawings which are for the purpose of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF A PREFERRED EMBODIMENT Shown in the drawings is a load neutralizing device 12 comprising a frame 14 of rectangular configuration, including a top 16 and a bottom 18 to which a pair of sides 20 are suitably secured. Centrally fixed to top 16, so as to extend upwardly therefrom is yoke 22 which is engageable by hoist means 23. Centrally located in bottom 18 is a hole 24 for passage of a shaft 26 disposed for vertical displacement in frame 14. A hook 28 for engaging the component to be lifted is attached to the end of shaft 26 that extends below bottom 18. Fixed to the top end of shaft 26 is a plate 30 parallel with top 16 and bottom 18 and vertically displaceable within frame 14. Six springs 32 are mounted between plate 30 and frame bottom 18, as hereinafter described, so as to be compressed therebetween when a load is applied to hook 28, with a row of three springs symmetrically disposed on opposite sides of shaft 26. A pair of buffer mechanisms 34 are mounted between frame top 16 and frame bottom 18 on opposite sides of shaft 26 and between the two rows of springs 32, as shown in FIG. 1.

Each of the springs 32 is coiled around a guide rod 36 which is threadingly engaged at one end to frame bottom 18 and at the opposite end thereof extends with a minimum tolerance, through a cooperating hole 40 in frame top 16. Each of the guide rods 36 passes through a corresponding aperture 42 in plate 30 to permit slidable displacement thereof relative to guide rods 36. Springs 32 are preferably preloaded, when installed between plate 30 and frame bottom l8,'and are thereby compressed between the free lengths and the solid heights thereof to reduce the size of frame 14 and permit the use of springs having low spring rates.

Each of the buffer mechanisms 34 includes a piston rod 46 which is fixed at one end to frame bottom 18 with the opposite end extending through a hole 48 in frame top 16. Located on piston rod 46 between the ends thereof is a piston 50 disposed within a slidable cylinder 52 fixed to plate 30 for vertical displacement therewith in frame 14. A cylindrical bearing portion 56 surrounds the upper end of piston rod 46 in sliding engagement with hole 48. Threadingly engaged within the bottom end of cylinder 52 is a bushing 58 in slidable guiding contact with piston rod 46. A similar bushing 60 is threadingly engaged within the top end of cylinder 52 in equivalent guiding contact with piston rod 46. An O-ring 62 is seated on piston 46 within each of the bushings 58 and 60 and a similar but larger diameter O-ring 63 is located between each bushing and the interior of cylinder 52 to seal a quantity of hydraulic fluid 64 therein. The diameter of piston 50 is slightly smaller than the internal diameter of cylinder 52 thereby permitting a predetermined amount of hydraulic fluid 64 to pass therebetween, when the cylinder is moved relative to'piston S by the vertical displacement of plate 30, to thereby buffer the movement thereof relative to frame 14. To provide load neutralizing device 12,with a continuous buffering action over a limited range of displacement of the lifted load, cylinder 52 is only partially filled with hydraulic fluid 64, thereby forming an air bubble 65 therein. The high compressibility of air bubble 6S permits easy displacement of the lifted load within a limited range.

A rod 66 extends outwardly from the exterior periphery of plate 30 through a vertically elongated slot 68 in one of the sides and mounted to such rod is a pointer 70 which is movable along a scale 72 during the displacement of plate 30 within frame 14. Such scale 72 is mounted to side 20 by a suitable screw 74 which passes through a vertical slot 76 therein and permits scale 72 to be adjusted relative to frame 14. An 0 mark 78 is inscribed on scale 72 intermediate the length thereof. When a load is lifted by hoist means 23 and scale 72 is vertically adjusted so that the 0 mark is in alignment with pointer 70, any subsequent change in the load imposed on the device, as by interference between the lifted and stationary components, will be visually indicated.

Where, forexample, weight neutralizing device 12 is adapted to handle loads of between 700 and 1,300 pounds, springs 32 are selected which withstand together, without being compressed to solid heights, a load of at least 1,500 pounds. Each of the six springs 32, therefore, must be able to carry a load of 250 pounds. In the described embodiment, each spring 32 has a free length of 12 inches and when compressed six inches it develops 250 pounds of pressure so as to have a spring rate of 41.6 pounds per inch. When installed, each spring 32 is compressed to 9-% inches so that the six springs effect a total preload of 562 pounds which is 2.25 (the distance of the compression) times 250 (the combined spring rate of the 6 springs).

With each spring 32 having a spring rate of 4L6 pounds per inch, the force necessary to move the load by weight neutralizing device 12 is the number of the springs multiplied by the spring rate per inch of one thereof and the distance the load is to be displaced. Thus, with this embodiment, the force required to manually move a load up or down l/l6 inches is 6 X 41.91, 1,6. 9: linosns.

if it is preferable to move the load manually with less force, springs 32 are selected having a lower spring rate. For example, if the spring rate per inch for each spring 32 is pounds then the force required to displace the load the same distance i 6 2 2 5j l 6 o r 9 .i1 pounds. Or, the number of springs 32 can be reduced 2th:; teasersmirsinith tour. sprin s is, t ..4 1. 6 or 10.4 pounds.

In order to lift a component into position to mate with another component, yoke 22 on weight neutralizing device 12 is attached to hoist means 23 and hook 28 is engaged with the component to be lifted. As device 12 is initially lifted, springs 32 are compressed between bottom 18 of frame 14 and plate 30 to the point where the developed force equals the weight of the lifted component. Since the load capacity of each spring 32 and the preload thereon was specifically selected to neutralize any load within a given range, once the zero equilibrium of device 12 has been reached, screw 74 is loosened and scale 72 vertically adjusted until the 0 graduation 78 is in alignment with pointer 70. Then the component is hoisted into the vicinity of the stationary component to be inspected and can, thereafter, be manually raised or lowered with ease into actual alignment therewith due to the zero equilibrium condition thereof. As the lifted component is moved relative to the other component to be inspected, any interference or binding therebetween can be felt by the inspector or visually determined by watching pointer for any fluctuation thereof relative to the 0" graduation 78 on scale 72. The other graduations on scale 72 are spaced to indicate the extent of the force involved in the manual adjustment imparted to the lifted component.

In the event the required manual manipulation of the lifted component is excessively resisted by springs 32, a new equilibrium position thereof may be readily attained without interrupting the existing engagement thereof with the stationary component. This is accomplished merely by holding the weight neutralizing device 12 against vertical movement and actuating hoist means 23 in the proper direction until pointer 70 is returned into alignment with the 0 mark 78. Thereupon, the required manual manipulation of the lifted gauge can be continued until excess resistance by springs 32 is again encountered. With this technique, the manual movement ofthe lifted component is not limited to the distance to which springs 32 can be compressed or extended at any one time within the interior of frame 14.

The foregoing disclosure and description of the invention is illustrative only. Various changes may be made within the scope of the. appended claims without departing from the spirit of the invention.

I claim:

1. A method for mechanically hoisting a first member into position for subsequent horizontal movement into mating engagement with a second member comprising the steps of,

inserting balancing springs between a mechanical hoist and said first member to neutralize the weight thereof and establish a zero equilibrium position relative to said mechanical hoist as said first member is lifted into the vicinity of said second member,

manually positioning said first member into alignment with said second member,

thereafter continuing to manually adjust the vertical position of said first member in order to maintain the alignment thereof with said second member during the completion of the required engagement therebetween,

selectively actuating said hoist relative to said first member to restore said springs to said position of zero equilibrium without disturbing the alignment between said first and second members whereby the force required to manually adjust said first member relative to said second member can be kept below a given level, and

continuously buffering the displacement of said balancing springs to eliminate surging thereof during the entire relative movement between said first member and said hoist. 

1. A method for mechanically hoisting a first member into position for subsequent horizontal movement into mating engagement with a second member comprising the steps of, inserting balancing springs between a mechanical hoist and said first member to neutralize the weight thereof and establish a zero equilibrium position relative to said mechanical hoist as said first member is lifted into the vicinity of said second member, manually positioning said first member into alignment with said second member, thereafter continuing to manually adjust the vertical position of said first member in order to maintain the alignment thereof with said second member during the completion of the required engagement therebetween, selectively actuating said hoist relative to said first member to restore said springs to said position of zero equilibrium without disturbing the alignment between said first and second members whereby the force required to manually adjust said first member relative to said second member can be kept below a given level, and continuously buffering the displacement of said balancing springs to eliminate surging thereof during the entire relative movement between said first member and said hoist. 